Continuous Wavelet Transforms for Simultaneous Spectral Determination of Trimethoprim and Sulphamethoxazole in Tablets

Abstract

A new signal processing approach was developed to improve the simultaneous spectrophotometric determination of trimethoprim (TMP) and sulphamethoxazole (SMX) in their binary mixtures without using any chemical pre-treatment. This approach was essentially based on the continuous wavelet transform (CWT) of the absorption spectra of the target compounds and their samples. A set of continuous wavelet transforms was applied. Biorthogonal with 2.4 order (BIOR2.4), Coiflets with 2 order (COIF2), Daubechies with 3 order (DB3) and Haar (HAAR) were found to be suitable for the quantitative resolution of the two-component mixture containing TMP and SMX compounds. The confirmation of the determination results obtained by applying the BIOR2.4, COIF2, DB3 and HAAR wavelet families was achieved by first derivative spectrophotometry (DS1) analysis of the same mixtures. The validation of the above-mentioned signal processing methods was tested by analyzing various binary mixtures of the related compounds, and by using the standard addition technique. The simultaneous determination of TMP and SMX in commercial tablets was assessed by using the proposed signal processing tools.